The chemokine CXCL12 and its receptor CXCR4 are expressed widely in human cancers including ovarian cancer, where they are associated with disease progression at the levels of tumor cell proliferation, invasion, and angiogenesis. Here we used an immunocompetent mouse model of intraperitoneal papillary epithelial ovarian cancer to demonstrate that modulation of the CXCL12/CXCR4 axis in ovarian cancer has multimodal effects on tumor pathogenesis associated with induction of antitumor immunity. siRNA-mediated knockdown of CXCL12 in BR5-1 cells that constitutively express CXCL12 and CXCR4 reduced cell proliferation in vitro and tumor growth in vivo. Similarly, treatment of BR5-1-derived tumors with AMD3100, a selective CXCR4 antagonist, resulted in increased tumor apoptosis and necrosis, reduction in intraperitoneal dissemination, and selective reduction of intratumoral FoxP3+ regulatory T-cells (T-regs). Compared to controls, CXCR4 blockade greatly increased T cell-mediated antitumor immune responses, conferring a significant survival advantage to AMD3100-treated mice. In addition, the selective effect of CXCR4 antagonism on intratumoral T regulatory cells was associated with both higher CXCR4 expression and increased chemotactic responses to CXCL12, a finding that was also confirmed in a melanoma model. Together, our findings reinforce the concept of a critical role for the CXCL12/CXCR4 axis in ovarian cancer pathogenesis, and they offer a definitive preclinical validation of CXCR4 as a therapeutic target in this disease.

Little is known about the mechanisms that underlie Brca1-associated ovarian tumorigenesis, mainly due to the lack of an appropriate experimental model. We developed genetically defined primary mouse ovarian surface epithelial (OSE) cell lines in which the loss of functional Brca1 and p53 recapitulates the events that are thought to occur in early ovarian cancer development in patients with Brca1 mutations. This system allows for the introduction of additional oncogenes that are thought to cooperate with the loss of Brca1 and p53 to induce tumorigenesis. We showed that Myc is sufficient to induce transformation of ovarian cells that are deficient for both Brca1 and p53 but not sufficient for the transformation of cells that are deficient for either Brca1 or p53. The transformed Brca1-deficient OSE cells display an increased number of centrosomes, acquire complex chromosome aberrations, and lack Rad51 nuclear foci in the presence of DNAdamaging agents, such as mitomycin C and cisplatin. Immunocompetent mice injected with transformed OSE cells develop tumors that resemble human metastatic serous ovarian carcinoma, the most common type of ovarian cancer in women. Consistent with the reported platinum chemosensitivity in patients with Brca1-associated ovarian cancer, the Brca1-deficient OSE cells have increased sensitivity to the DNA-damaging agent cisplatin, whereas sensitivity to the microtubule poison paclitaxel is similar between Brca1 wildtype and Brca1-deficient cells. The Brca1 wild-type and Brca1-deficient mouse ovarian tumors and cell lines provide a new experimental system for the evaluation of therapies that target the Brca1 pathway. (Cancer Res 2006; 66(18): 8949-53)

Small interfering RNAs (siRNAs) mediate cleavage of specific, complementary mRNA sequences and thus regulate gene expression. Not surprisingly, their use for treatment of diseases that are rooted in aberrant gene expression, such as cancer, has become a paradigm that has gained wide interest. Here, we report the development of dendrimer-conjugated magnetofluorescent nanoworms that we call “dendriworms” as a modular platform for siRNA delivery in vivo. This platform maximizes endosomal escape to robustly produce protein target knockdown in vivo, and is tolerated well in mouse brain. We demonstrate that siRNA-carrying dendriworms can be readily internalized by cells and enable endosomal escape across a wide range of loading doses, whereas dendrimers or nanoworms alone are inefficient. Further, we show that dendriworms carrying siRNA against the epidermal growth factor receptor (EGFR) reduce protein levels of EGFR in human glioblastoma cells by 70−80%, 2.5-fold more efficiently than commercial cationic lipids. Dendriworms were well-tolerated after 7-days of convection-enhanced delivery to the mouse brain and in an EGFR-driven transgenic model of glioblastoma, anti- EGFR dendriworms led to specific and significant suppression of EGFR expression. Collectively, these data establish dendriworms as a multimodal platform that enables fluorescent tracking of siRNA delivery in vivo, cellular entry, endosomal escape, and knockdown of target proteins.

The lack of second-line treatment for relapsed ovarian cancer necessitates the development of improved combination therapies. Targeted therapy and immunotherapy each confer clinical benefit, albeit limited as monotherapies. Ovarian cancer is not particularly responsive to immune checkpoint blockade, so combination with a complementary therapy may be beneficial. Recent studies have revealed that a DNA methyl transferase inhibitor, azacytidine, alters expression of immunoregulatory genes in ovarian cancer. In this study, the antitumor effects of a related DNA methyl transferase inhibitor, decitabine (DAC), were demonstrated in a syngeneic murine ovarian cancer model. Low-dose DAC treatment increases the expression of chemokines that recruit NK cells and CD8 þ T cells, promotes their production of IFNg and TNFa, and extends the survival of mice bearing subcutaneous or orthotopic tumors. While neither DAC nor immune checkpoint blockade confers durable responses as a monotherapy in this model, the efficacy of anti-CTLA-4 was potentiated by combination with DAC. This combination promotes differentiation of na€ ve T cells into effector T cells and prolongs cytotoxic lymphocyte responses as well as mouse survival. These results suggest that this combination therapy may be worthy of further consideration for improved treatment of drug-resistant ovarian cancer.

Variation in DNA repair capacity, which is believed to be largely determined by genetic traits, is linked to risk of certain cancers. The Asp312Asn and Lys751Gln polymorphisms in the xeroderma pigmentosum complementary group D (XPD) gene may alter DNA repair capacity. We thus examined the hypothesis that these 2 XPD polymorphisms are associated with risk of lung cancer via a large hospital-based, case-control study among Chinese. The study subjects consisted of 1,006 patients with primary lung cancer and 1,020 age-and sex-matched population controls. XPD genotypes were determined using PCR-RFLP techniques, and the associations between genotypes and risk of lung cancer were estimated by odds ratios (ORs) and their 95% confidence intervals (CIs) calculated by unconditional logistic regression. The DNA repair system plays an important role in protecting against mutagenesis and carcinogenesis. It has been documented that the defect in DNA repair causes several hereditary cancer syndromes 1 and the development of some common sporadic cancers may also associated with reduced DNA repair capacity. [2][3][4] Accumulating evidence indicates that variation in DNA repair capacity is likely to be largely determined by genetic traits. The defect of DNA repair often results from gene mutations. However, single nucleotide polymorphisms (SNPs), when located within the coding and/or regulating regions of the gene, can also spoil DNA repair capacity due to the amino acid substitution or diminished protein expression. XPD (xeroderma pigmentosum complementary group D), an important DNA repair protein, encodes an evolutionarily conserved ATP-dependent helicase that participates in both nucleotide excision repair and basal transcription as part of the transcription factor TFIIH. 5 Mutations at different sites in XPD that destroy XPD protein function cause 3 severe syndromes: Cockayne's syndrome, trichotiodystrophy and xeroderma pigmentosum, which exhibits a Ͼ1,000-fold incidence of sun-induced skin cancer and elevated risk of internal cancers. 6,7 Several SNPs have also been identified in the XPD locus. Among them, a G-to-A transition in codon 312 of exon 10 results in an Asp3 Asn substitution in an evolutionarily conserved region, and another transversion, A-to-C in codon 751 of exon 23, produces a Lys3 Gln substitution. 8 The 2 sites are reported to be in linkage disequilibrium and appear to have phenotypic significance, although contradictory results exist regarding which allele is associated with impaired DNA repair capacity. 4,9 -14 Since XDP is one of the important components in the nucleotide excision repair (NER) and NER is the most flexible pathway that has the ability to remove a broad range of DNA damage such as BPDE-DNA adducts induced by benzo(a)pyrene, 15,16 a major constituent of tobacco smoking, the impact of these 2 genetic variations in XPD on risk of cancer in addition to skin cancer has been attracting research interest. Some case-control studies have been conducted in different ethnic populations to investigate ...

No abstract

Small cell neuroendocrine carcinoma (SCNEC) of the uterine cervix is a rare but extremely aggressive tumor. While high-risk human papillomavirus (HPV) is involved at an early stage of oncogenesis in many tumors, additional driving events have been postulated to facilitate the progression of SCNECs. Identification of oncogenic drivers could guide targeted therapy of this neoplasm. Clinicopathologic features of 10 cervical SCNECs are reported. Analyses included immunohistochemical evaluation of p16, p53, synaptophysin, and chromogranin expression; in situ hybridizations and polymerase chain reaction for high-risk HPV and/or HPV 18; and next-generation sequencing based on a 637-gene panel. The patients ranged in age from 28 to 68 years (mean, 45.6 y; median, 40.5 y). All tumors had diffuse p16 and synaptophysin expression. All but 1 tumor was positive for chromogranin (extent of staining ranged from focal to diffuse). HPV 18 was detected in 6 tumors and HPV 35 in 1 tumor. At least 1 driver mutation was detected in 8 tumors. Four cases harbored TP53 somatic mutations, 3 of which correlated with an aberrant p53 staining pattern. Four PIK3CA mutations (p.G106A, p.N345T, p.E545K, and p.E545D) were detected in 3 tumors, 2 of which also harbored TP53 mutations. Oncogenic driver mutations involving KRAS, Erbb2, c-Myc, NOTCH1, BCL6, or NCOA3 were detected in 4 tumors. Mutations in caretaker tumor suppressors PTEN, RB1, BRCA1, BRCA2, and ARID1B were also identified in 4 tumors that commonly coharbored activating oncogenic mutations. Targeted next-generation gene sequencing identified genetic alterations involving the MAPK, PI3K/AKT/mTOR, and TP53/BRCA pathways in SCNECs. The presence of genetic alterations that are amenable to targeted therapy in SCNECs offers the potential for individualized management strategies for treatment of this aggressive tumor.

Esophageal squamous cell carcinoma (ESCC), which is prevalent in China, is believed to be induced by environmental carcinogens. Accumulating evidence has shown that individual variation in DNA repair capacity resulting from genetic polymorphism influences risk of environmental carcinogenesis. We therefore investigated the associations between genetic polymorphisms in the DNA repair genes XRCC1 (Arg194Trp and Arg399Gln) and XPD (Asp312Asn and Lys751Gln) and risk of ESCC in an at-risk Chinese population. Genotypes were determined by a PCR-based approach in 433 patients with ESCC and 524 frequency-matched normal controls. We found that individuals with Trp/Trp genotype at XRCC1 Arg194Trp site had a 2-fold increased risk of this disease compared to Arg/Arg genotype (adjusted OR ‫؍‬ 1.98; 95% CI 1.26 -3.12). Furthermore, when compared to Arg/Arg and Arg/Trp genotype combined, homozygote for Trp/Trp genotype significantly increased the risk of developing ESCC, with the adjusted OR being 2.07 (95% CI 1.34 -3.20). However, the XRCC1 Arg399Gln polymorphism was not significantly associated with risk of ESCC, with the adjusted OR being 0.87 (95% CI 0.55-1.37). Neither Asp312Asn nor Lys751Gln polymorphisms in the XPD gene influenced risk of ESCC in our study. These findings suggest that DNA repair gene XRCC1 but not XPD might play a role in esophageal carcinogenesis and might represent a genetic determinant in the development of the cancer.